Not carrying a US-passport, I avoid immigration at LAX when ever possible - lines (and organisation) for immigrants can often be terrible (about every second time I had to ait over 50 minutes, the maximum was once, when arriving together with PremEx late afternoon from FRA on LH, the UA immigration terminal was already closed and we had to go though Bradley, I waited 2 hours and 15 minutes ... and poor PremEx) had to wait outside for me all that time ... .

On the US westcoast it is for me much easier through SFO.

On the US estcoast, I prefer BOS for immigration.